1. Field of the Invention
This invention relates to sheaths and introducers, which are utilized in a human heart, which has been altered by heart disease. More particularly, this invention relates to a precurved, guiding introducer for introducing specialized medical devices into the coronary sinus of a heart with cardiomyopathy and a process for introduction of those devices into the coronary sinus utilizing the precurved, guiding introducer.
2. Description of the Prior Art
Many medical procedures require the introduction of specialized medical devices into the human heart. For example, electrical leads, such as pacemaker leads, defibrillation leads or leads used for cardioversion, or specialized catheters are frequently placed at specific locations within the heart to perform specialized cardiac procedures. Many of these medical devices, such as pacemaker leads, are very pliant and flexible. This flexibility is necessary to prevent damage, particularly to the patient's vasculature, during the period of time those products are present in the patient. However, because of this flexibility, it is quite difficult to advance these devices through the patient's vasculature into the heart without the use of some stiffening element with the device. For example, one method of stiffening certain medical devices is to introduce a stylet into the lumen of the medical device.
The typical procedure for introducing these devices into the heart requires passage through the patient's vasculature. One early approach to introduction of devices into the vasculature was to surgically cut an opening into the patient's vasculature. However, there are several disadvantages to this procedure. To address these disadvantages, percutaneous methods have been developed to create openings in the vasculature. Once an opening is created, frequently by use of a hollow needle, a dilator is usually inserted into the vasculature, which gradually increases the size of the opening. The dilator has a tapered end, which spreads apart the tissue at the puncture sight as it is advanced through the vasculature. Often the dilator will contain a lumen through which other medical devices may also be inserted into the vasculature.
As an example, in a typical procedure for introduction of an electrode lead into the heart, a guidewire is first introduced through the vasculature into the appropriate chamber of the heart. With the guidewire in place, a catheter/introducer or dilator/introducer combination is then passed over the guidewire and directed into the patient's body. The catheter or dilator is then removed from the introducer. The introducer then provides a platform from which the lead may be introduced into the heart, frequently with a stylet placed within the lumen of the lead to assist in stiffening the structure of the lead and also to permit precise placement of the device within the heart.
With conventional introducers, the maximum diameter of the pacemaker lead that can be inserted is no larger than the lumen of the introducer. This limitation created a significant problem because of the nature of pacemaker leads. Frequently, the pacemaker lead's proximal end contained an electrical connector for connection to the pulse generator. Because the size of the connecter is often larger than the diameter of the lumen of conventional cardiac introducers or sheaths, the invention contemplates that these introducers or sheaths are splittable, sliceable or tearable to assist in the insertion of these electrode leads. Once the introducer directs the placement of the medical device, such as an electrode lead, into the body, the splittable, sliceable or tearable introducer is separated lengthwise as it is withdrawn from the body. By being separable by some means, the size of the lumen of the splittable, sliceable or tearable introducer can remain relatively small as it need be no larger than is necessary for passage of the distal tip of the medical device through the lumen of the introducer. In addition, the prior art uses a splittable hemostatic valve, such as shown in U.S. Pat. Nos. 5,125,904 and 5,312,355, that is utilized in combination with a splittable sheath for introduction of a pacemaker electrode into a patient.
While specialized medical devices are utilized throughout the human body, many have been used in the heart, in general and specifically in the coronary sinus. The coronary sinus is the largest cardiac vein in the heart and serves as a venous conduit from smaller veins within the myocardium to the right atrium. A tissue fold or primitive valve covers the coronary sinus ostium to prevent blood from backflowing into the coronary sinus as it is being pumped out of the right atrium. Located within the right atrium, generally, above the coronary sinus is an oval depression called the fossa ovalis. Between the inferior vena cava and the coronary sinus ostium is the Eustachian ridge. The location of each of these elements may vary from patient to patient.
The coronary sinus is often used for electrophysiological procedures in the heart, including both diagnostic and treatment procedures. The coronary sinus can also be used as a location for pacing both the left and right sides of the heart. Gaining access to the ostium of the coronary sinus is a very difficult procedure, especially because of the large number of similar anatomical structures located near the coronary sinus within the right atrium. It is especially difficult because these anatomical structures do not show up on a fluoroscope.
Current procedures available for introduction of devices such as pacemaker leads, implantable defibrillator leads, specialized catheters or devices used for cardioversion into the coronary sinus are frequently time consuming and difficult. To address this problem for a particular type of diagnostic catheter, various researchers have devised precurved, coronary sinus catheters, which because of their curvature, can be advanced through the patient's vasculature directly into the coronary sinus, where it can be used for diagnostic and treatment procedures such as disclosed in U.S. Pat. No. 6,277,107.
While several preshaped or biased introducers have been proposed, the shapes provided are still difficult to manipulate successfully and quickly into the coronary sinus. It typically takes a considerable amount to time and physician skill to manipulate these shaped introducers successfully into the opening of the coronary sinus.
The presence, diameter, angulation, and tortuosity of veins as may be visualized by retrograde venography determine their acceptability for the placement of a lead in a predetermined location. Despite the considerable variability of the coronary venous system among patients, in one study a lateral vessel for lead introduction was available in 82%, and a posterior or lateral vessel was available in 99% of individuals within a patient population that could potentially benefit from a lead on the left ventricle. Similar variations in anatomic location are present in the coronary sinus os. See Eckhard Meisel, MD et. al., “Investigation of Coronary Venous Anatomy by Retrograde Venography in Patients With Malignant Ventricular Tachycardia”, Circulation, 2001; 104:442.
Accordingly, it is an aspect of this invention to disclose an optimally shaped device, which assists in the efficient placement of medical devices particularly small, flexible medical devices, such as electrode leads, into the coronary sinus, even by physicians without a high level of experience in using the device.
It is a further aspect of this invention to disclose an introducer for use by ordinarily skilled physicians without specific experience with the introducer to allow a medical device, such as a flexible lead for use with a pacemaker, defibrillator or for cardioversion, to be introduced into the coronary sinus.
Another aspect of this invention is to disclose a fixed shape introducer to be used for the introduction of medical devices into the coronary sinus by ordinarily skilled physicians without specific experience with the introducer.
Another aspect of the invention is to disclose a fixed shaped introducer which can be used in a process for the introduction of medical devices into the coronary sinus without using a guidewire by ordinarily skilled physicians without specific experience with the introducer.
Another aspect of the invention is to disclose a process for the introduction of flexible medical devices into the coronary sinus of the human heart using a precurved guiding introducer by ordinarily skilled physicians without specific experience with the introducer.
These and other aspects are obtained by the design of the device of the present invention and by the process disclosed herein.